Die casting machine



Mw M WW j. --mmwe UAL @,EQJLE DIE CASTING MACHINE Filed Nov. l, 1963 5Sheets-Sheet l May 16, m57 HARM/v1@ ETAL wfi DIE CASTING MACHINE FiledNov. l, 1963 5 Sheets-Sheet 2 INVENTORS j JURGEN HAnTwlG ,VICTORMANDoRr-',JR.

CRESGENZO Ff FULGENZI, ROBERT H,NORRIS MAYNARD W. ROISEN, PETER A.LERCHMay 16 1957 J. HARTWIG ETAL 3,3`9,72

DIE CASTING MACHINE Filed Nov. l, 1963 5 Sheets-Sheet C- gg fia" M 'y wgn INVENTORS JURGEN HAnTwlGNlcron MANDORF, JR.

74 CRESCENZO E FULGENZI,ROBERT H. NORRIS MAYNARD W. ROISEN, PETER A4LERCH A T TORNEV May 16, w67 J. HARTWIG ETAL 3,319,792

DIE CASTING MACHINE Filed Nov. l, 1963 5 Sheets-Sheet 4 @mi v INVENTORSJ JURGEN HARTWIGNlc-ron MANDoRnJR.

WM@ 0 cREscENzo E ruLGENz|,RoBERT H.NoRR|s MAYNARD w. RolsEN, PETER A.LERCH ATTRNEV May 16, m57 J. HARTWIG ETAL 3,339,1@2

AD'IE CASTING MACHINE Filed Nov. l, 1963 5 Sheets-Sheet 5 JURGEN HAmwlG782 vlcToR MANDORF,JR

cRcscENzo E FuLsENza RoBERT H, NoRRls MAYNARD w. RolsEN PETER A LERCH3V/4&7) 4. www@ A 7` TORNEV United States Patent C York Filed Nov. 1,1963. Ser. No. 320,693 12 Claims. (Cl. 164-316) This invention relatesto an apparatus for die casting high melting point die casting alloyssuch as aluminum, magnesium, and the like. More particularly thisinvention is directed to a novel hot chamber die casting ap paratus ofthe submerged-plunger type.

In the art of die casting high melting point die casting alloys, theproduction rates are much lower than those used in die casting lowmelting point alloys such as lead, tin and zinc. In order to produce themost economical die casting, high production rates must be utilized. Upto the present time all aluminum die castings are made either byemploying an air injection machine or a coldchamber machine both ofwhich exhibit certain disadvantages which will be discussed hereinafter.Unfortunately heretofore high melting point alloys could not be die castin high speed submerged-plunger machines inasmuch as the castingtemperatures of such alloys are exceedingly high (lll F.-l250 F.) andsince the aluminum alloys have such an ainity for iron which is thecommon material of construction that they quickly attack and dissolve itby corrosive and erosive action.

In the air injection machine, there is a cast-iron closed vessel orchamber, conventionally known as a gooseneck disposed above a largemetal pot or holding furnace containing the molten metal to be die cast.The gooseneck is filled prior to each casting operation by dipping thespout of the gooseneck below the metal level. After filling thegooseneck, the spout is locked against a metallic mold or die andpressure is applied against the metal by compressed air admitted througha valve which forces the metal through the spout to till the die. Whenthe valve is subsequently closed, the air above the metal is releasedand exhausted, and the gooseneck then may be lowered and refilled againto repeat the casting cycle.

One of the disadvantages of this type of machine is its susceptibilityto iron erosion and corrosion and its relatively low operatingpressures. Although theair injection machine can be used for highmelting point alloys, owing to the lower pressures used, the casting islikely to be less dense and more porous than when made in asubmerged-plunger (hot chamber) machine. Another disadvantage of thistype of machine is that if casting aluminum iron pickup is relativelyhigh since the gooseneck is tilted and moved .in the molten aluminumboth during each casting cycle thus causing severe agitation which isconducive to high erosion rates.

In the cold-chamber machine which is predominately used for aluminumalloys the molten-metal reservoir is separated from the casting machine,and just enough metal for one casting is normally ladled by hand througha port or pouring slot of a small chamber, from which it is then forcedinto the die under high pressure usually by a hydraulically operatedplunger. As the plunger initially advances, it seals the port, andforces the charge into the locked die under high pressure which commonlyranges from about 6,000 to 20,000 p.s.i., and in some cases pressures ashigh as 60,000 p.S.i. are used, depending upon the size and type ofcastings made. Some of the disadvantages of the cold-chamber machine arethe necessity for high injection pressures and the metallurgicallypoorer casting which results due to the chilling of the molten metal inthe chamber. Moreover, for the same size casting the cold chambermachine is somewhat slower than the submerged-plunger type because ofladling time.

The hot chamber machines presently available are mainly suited for zincalloys and other low melting point alloys. In this type of machine,there is a main metal pot in which is immersed a lixed cylinder having aspout rmly connected to a nozzle locked against a die cavity. A pistonoperating in the cylinder is raised to uncover an inlet port below themetal level in the pot. Once the molten metal fills the interior of thecylinder, the piston 1s forced downward causing the metal to flow outthrough the spout into the die. As soon as the metal solidifies 1n thedie, the piston is withdrawn, the die opened and the die casting isthereafter ejected. Then the die is closed and locked again and thecycle is repeated. This type of machine is extremely rapid in operationand gives excellent results and as a result there has been a markedtendency and continued effort on the part of the die castmg industry todevelop a hot chamber machine also for the casting of aluminum. This hasnot been possible to date because of the corrosion problems associatedwith handling molten aluminum and of the numerous design problemsencountered in the use of refractory materials.

Many of prior art patents `are illustrative of the difculties which areinherently associated with die casting high melting point alloys, as forinstance, aluminum. For example, United States Patent No. 2,195,360 isdevoted to minimizing the contact with the molten metal by conveying itfrom a crucible to the feed tube of the die by means of compressed air;thereafter, the metal is forced mto the die by operation of a plunger asis conventionally done in a cold chamber machine. Since only momentarycontact with the molten metal is experienced, this type apparatusattempts to solve the problem of deleterious corrosive effect on theworking parts of the assembly by simply avoiding and minimizing contactwith the molten metal. In United States Patent 1,954,775 a similarapparatus impresses a vacuum across the die cavity, gate, etc. to permitthe molten metal in the crucible to be forced upwardly by atmosphericpressure through a feeder tube and into the plunger chamber at whichtime the plunger will be activated to force the metal from the chamberinto the die cavity; and United States Patent 2,837,792 discloses a likeapparatus which produces a sub-atmospheric pressure in theplunger-cylinder sucient to draw molten metal into the cylinder througha supply tube. It is noteworthy to remark at this time that all thesepatents teach away from a hot chamber or submerged-plunger machine andinstead refer specifically to means for increasing the casting rate of acold chamber machine by utilizing compressed air or a vacuum to till thepouring slot of same. Even with such apparatus, there is much to bedesired with respect to increasing the rate of production of aluminumdie castings, improving casting quality and die life, minimizing scraprates, `and of being able to die cast larger sizes than those presentlycast.

Although numerous attempts have been directed at adapting the hotchamber principle for casting the high melting point alloys such asaluminum, none were successfully achieved since the shot cylinders ofsuch machines invariably failed in a very short period of time due tothe extremely corrosive and erosive action of the molten aluminum, andbecause of the apparently insurmountable design problem associated withthe use of various refractory materials.

It can be surmised that these failures occurred because of the manyleakage problems which developed, since the high melting point diecasting alloys corrode and erode most metallic engineering `materialssuch as tool steels and cast iron, especially if the elements of theapparatus exposed to the molten aluminum are subject 3 to a rubbingaction. An interesting observation of molten aluminum in this regard isthat in a stagnant or quiescent state the molten aluminum attacks themetallic container at a substantially lower rate than when the metal isagitated.

Refractory materials, in general, possess much better resistance tocorrosion when compared to metallic engineering materials. Somerefractory materials, such as certain metallic oxides and nitrides, werefound to be undesirable and unsuitable for use with molten aluminumbecause they do not possess the requisite attributes required of them,such as high strength, hardness and density, resistance to thermalshock, oxidation at high temperatures and other forms of corrosion anderosion, and to other conditions that normally bring about thedeterioration and failure of such refractories. For materials which dopossess the said requisite attributes, it has been extremely diicult todesign a shot cylinder for a hot chamber die casting machine, since thephysical properties of the refractories used for making the shotcylinder were incompatible with those of the conventional materials ofconstruction, as for example iron and steel. The fabrication ofrefractories and ceramics in usable shapes has not been developed to apoint where they can be utilized as engineering materials for this typeof application. Moreover, because of the wide differences between thecoeicient of thermal expansion of iron versus most refractories appearedto restrict the use of most refractories to at most limited applicationsespecially to those of a static nature such as crucibles, vaporizingboats, etc.

Accordingly, it is the principal object of the present invention toprovide a hot chamber die casting machine for casting primarily highmelting point, lightweight die casting alloys.

Another object of the invention is to provide a shot cylinder assemblywhich is adaptable to hot chamber die casting machines of otherwiseconventional construction.

A further object is to provide means for the solution of the thermalexpansion problems which also allow for the precision alignment andoperational stability of the assembly.

A still further object is to provide means for protecting the shotcylinder assembly from mechanical damage and from thermal shock and toprovide practical means for the necessary maintenance and for theVreplacement of parts.

The novel apparatus of the invention by means of which these and otherobjects are achieved comprise a shot cylinder composed of acylindrically shaped housing member having a bored cavity therein and apiston assembly slidably engaged within the cavity both of which arecomposed of a refractory material which is resistant to corrosion anderosion by the metal to be cast. The cylinder is surrounded by aprotective sleeve which is secured to means for maintaining a sealbetween the housing and a gooseneck which connects the cylinder to a diecavity, said means applying a clamping pressure upon the shot cylinderwhich in turn bears upon a seal ring which seals the shot cylinder fromthe gooseneck of a die casting machine.

The shot cylinder of the instant invention will be made more readilyapparent by reference to the accompanying drawing of which FIGURE 1 is aside elevational view partly in section of a conventional die castingapparatus embodying the invention.

FIGURE 2 is a somewhat enlarged cross sectional view of the shotcylinder of the invention taken along the line 2 2 of FIGURE 1.

FIGURE 3 is an enlarged detail view in section taken on the line 3-3 ofFIGURE 1.

FIGURE 4 is a cross sectional view in elevation of a slightly modifiedshot cylinder.

FIGURE 5 is a side elevational view of a modified piston assembly foruse in the apparatus of FIGURE l.

FIGURE 6 is a side elevational view partly in section of anothermodified piston assembly for use with the apparatus of FIGURE l.

FIGURE 7 is also a side elevational view in section of yet anothermodified piston assembly; and

FIGURE 8 is a side elevational view in section of a modified piston andshot cylinder assembly.

As shown in FIGURE 1, a die casting machine in general consists of aholding furnace 10 which supports and maintains a melting Ibasin or pot12 at the desired casting temperature. A gooseneck assembly 14 issuspended within the pot 12 and it communicates with a die cavity 16.The die cavity 16 represents only a small portion of an overall diestructure of conventional design be it a single cavity, multiple-cavityor combination die. Other portions of the die structure such as themovable platen, ejector plate and toggles or hydraulic mechanism are notshown inasmuch as this equipment is of a standard nature and since itdoes not aid in contributing to an understanding of the invention. Asbest shown in FIGURE 2, the shot cylinder of the invention comprises apump unit or package including a piston assembly 18 and a housingassembly 20 disposed inside the main cavity 22 of the gooseneck assembly14. The piston assembly 18 is connected to a suitable power cylinder 24by means of a coupling 26.

The means for maintaining a seal between the shot cylinder and thegooseneck consist of said housing assembly 20 which comprises an upperholddown member 28 and preferably a lower sleeve 30 which is suitablyconnected to the holddown member 28. The sleeve 30 serves to protect andalign the shot cylinder assembly. The upper holddown member 28 isprovided with a ange 29 about its larger diameter; which flange 29 issecured to the top surface 32 of the gooseneck assembly 14 by means ofthe threaded studs 34 and compatible nuts 36, preferably of hex headshape. Of course, other suitable fastening methods may also be employedso long as they are capable of adjustment which must be madeperiodically during starting up operations which will be discussedhereinafter. As best shown in FIGURE 1, at the rear end 38 of thegooseneck assembly 14, apertures 40 are provided which enable the moltenmetal 42 situated in the pot 12 to enter the main cavity 22 thereof. Themolten metal level 54 is constantly maintained in the pot 12 byconventional means. A cylinder 48 and the lower protective sleeve 30 areprovided with apertures 44 and 46 respectively. These apertures 44 and46 enable the molten metal to fill passageway 52 and cylinder bore 50upon the upstroke of the piston assembly 18.

A replaceable nose insert 56 is provided in the upper end of thegooseneck assembly 14. The nose insert 56 is provided with a passageway58 which communicates through a nozzle 59 with the die cavity 16. If anywear takes place in these passageways, it will most likely occur at theuppermost portion of the approximate right angle turn of the passageway58. This is probably so since the severest rubbing and frictional actionof the molten metal is caused to occur in this area.

The bottom seal assembly which seals the cylinder 48 to the gooseneck 14is best seen in FIGURE 3. An annular shaped ring 60 is provided with agroove 62 preferably nearer to the inside diameter 64 of the ring 60 anda resilient corrosion resistance metal-ceramic cornposite seal member 66is disposed in the groove 62. The ring 60 distributes the compressiveload on the cylinder 48 thereby precluding any overstressing orfracturing of corners. The top 68 surface of the ring 60 as well as themating surface of the cylinder 48 are provided with fine surfacefinishes. A suitable seal member 66 is a spirally wound laminate ofasbestos and stainless steel and its inner and outer peripheral portionsare reinforced by a few layers of stainless steel. The spiral issuitably tack or spot welded together and ground to eliminate any burrsor beads formed by the weld. This seal member is resistant to the attackof molten aluminum and possesses sufficient compressibility andresilience so as to allow for some misalignment.

The piston assembly 18 comprises a sleeve 72 mounted on a stud 74 havinga flanged head 76. The stud 74 is preferably composed of a corrosion andheat resistant material. The tolerance between the inside diameter ofthe sleeve 72 and the diameter of the stud 74 is such that a positiveseal is maintained at operating temperatures between the bore of thesleeve 72 and the stud 74.

It should be pointed out at this time that the sleeve 72 and thecylinder 48 are composed of a hard, dense, high strength refractorymaterial which is resistant to high melting point die casting alloyssuch as aluminum, magnesium and the like. Some of the materials suitablefor these elements are the borides, carbides, and nitrides from theGroups lV-A, V-A, and VI-A of the periodic chart of the elements,aluminum oxide, and carbonaceous bodies coated with silicon carbide.Titanium diboride is a preferred material although the other materialsare also not affected by molten aluminum, zinc, copper and alloysthereof. The sleeve 30 in particular aids in protecting the brittlecylinder 48 from mechanical damage and also from thermal shock if thepump unit is removed from the gooseneck assembly 14 to the surroundingenvironment.

The stud 74 is secured to a member 75 which is in turn connected to thecoupling 26 by means of an adjustment stud 7S. As best shown in FIGURE2, the holddown member 28 is centered in the main cavity 22 of thegooseneck 14 by means of a finished pad 8f). This holddown member 2t;and the protective sleeve 30 in turn center and maintain in alignmentthe cylinder 48 and seal ring 60, with respect to the lower neck portionof the gooseneck 14.

Preparatory to the actual operation of the apparatus, the entire unitmust be gradually brought up to its operating temperature by starting upthe holding furnace and by positioning suitable gas burners atpredetermined positions in order that the nozzle section may also bebrought up to desired casting temperature. Once the molten metal isydispensed into the holding furnace, a soak period allows thetemperature of the equipment to become uniform throughout and to bestabilized. Thereafter the apparatus is constantly maintained at thecasting temperature by the furnace alone. No external heat sources areneeded once the apparatus is in operation. The apparatus cools downgradually once the furnace is turned off and of course the pump unit isremoved therefrom so as not to cause it to be frozen in the remainingbath of metal left over in the pot. Thus, when the apparatus is normallyrestarted, the holding furnace is heated so as to melt the metal in thepot. The pump assembly is also heated to temperature independently andthen it is assembled into the apparatus. Due to the differentcoeflicients of thermal expansion for the refractory material and forthe gooseneck and associated components which are generally of castiron, it is necessary at predetermined intervals to retorque the nuts 36so as to maintain a constant seal pressure at the bottom seal ring 60.If desired, springs may be used so that the holddown member 28 isconstantly forced against the cylinder 48.

yIn operation, the molten metal 42 passes through th-e apertures 40 inthe rear wall of the gooseneck 14 and through suitable apertures 46 inthe protective sleeve 30 and thence through the inlet aperture 44 of thecylinder 48. Once the bore 5i) of the cylinder 4S is filled, theapparatus is activated whereby the piston assembly 18 is driven downinto the bore 50 thus causing the molten metal in the cylinder 48 to beforced under high pressure -into the passageways 52, 58 and then intothe die cavity 16. As the piston 18 returns on its upward stroke ituncovers the inlet apertures 44 of the cylinder 43 and the cycle is thusrepetitive thereafter. Of course, the molten metal level 54 in theholding furnace 10 must be maintained above a minimum level. It ispointed out at this time that inclined apertures 84 are also provided inthe gooseneck 14 in order that the molten metal 42 in the main cavity 22may be drained therefrom as the gooseneck 14 is raised from the pot 12.

A modified cylinder assembly which may be employed in the practice ofthe invention is shown in FIGURE 4. In this construction, the bottomscat of the cylinder 88 consists of a conical surface 86. This surface86 mates with a corresponding spherical or conical surface machined onthe lower neck portion of the gooseneck 14. At the upper end of thecylinder 88 are two alignment surfaces 90 and 92, one at about theoutside diameter and the other at about the inner diameter. The seatsare of a design such that when the apparatus is cold, the overallalignment is governed by the outside surfaces 90 which are in Contactwith each other whereas the inner surfaces 92 have some clearancebetween them. As the apparatus becomes hot, the top portion 94 of thecylinder assembly being made of metal expands radially faster than therefractory cylinder 88, thus as the inner surfaces 92 come into Contactwith each other and control the overall alignment the outer surfaces 911begin to part. If desired, a protective sleeve may also be provided withthis particular shot cylinder arrangement.

In FIGURE 5 a modied piston assembly is illustrated. This assembly isadapted for use in the apparatus of FIGURE l. As shown therein, thepiston 96 is a monolithic refractory member releasably secured to alower holder 98 which in turn is swivelly connected to an upper holdingdevice 100. The lower holder 98 comprises two halves which are boltedtogether about the head and reduced neck portion 102 of the piston 96.The lower end of the piston may be suitably beveled as at 104 in orderto facilitate assembly into the cylinder 106 and to preclude chippingand burring of the edges thereof. The upper holding dev-ice is ofconventional design and comprises a pair of mating conical discs 108 and110 which permit a slight amount of misalignment between the piston 96and the cylinder 106.

As shown in FIGURE 6 another modified piston assembly is illustrated. Inthis embodiment, the piston 112 -is similar in construction to thepiston assembly shown in FIGURES l and 2 except for the upper portionthereof. In FIGURE 6, the nut 114 is thread-ed onto the end of the stud116 and locked in place by means of a suitable set screw 118 bearingagainst the threaded stud 116. The nut 114 in turn lis prevented fromrotation by means of a second set screw 120 disposed in the holder 122.The nut 114 and stud 116 once locked are free to move axially thedistance permitted by expansion and operating temperatures; set screw120 serving as a key to prevent rotation. The upper portion 124 of theholder 122 is swivelly connected to the connecting rod 126 in a mannersimilar to the construction shown in FIGURE 5. End cover 12S maintainsthe seal between the connecting rod 126 and the holder 122.

In FIGURE 7, a modified piston assembly comprising a plurality of ringsis shown. This type of structure is also suitable for use in theapparatus in FIGURE l. As shown therein, the stud 13@ is similar to thestuds of FIGURES l, 2 and 6 although it contains alternate rings 132 and134 composed respectively of metal and a refractory material, preferablytitanium diboride. The titanium diboride rings 134 are provided with aslight clearance on their inside diameters 136 and the outside diameters138 are such that the piston assembly may be readily assembled into thecylinder 140. The metal rings 132 are fit about the stud 130 andprovided with clearances on their inside and outside diameters. Theserings are held together in interface contact by means of the connectingrod 142 which is threaded and pinned to the stud 130. By thisconstruction, a greater degree of misalignment of the piston assembly inthe cylinder 140 can be tolerated and yet a good sliding fit ismaintained between the rings 134 and the bore 144 of the cylinder 7 140.Although it is disclosed that the rings are alternately of a metal and arefractory material, all of the rings may suitably be composed of arefractory material.

In FIGUREl 8 another embodiment of the invention is illustrated. Asshown there the die casting machine is generally of the sameconstruction as that shown in FIGURE 1 except for the piston assembly150 and the bottom seal assembly 152 which are somewhat different. Thecylinder 154 is basically identical to the cylinder describedhereinbefore. The piston assembly 150 includes a rod 156 threaded atboth ends, the lower end of which contains a head 158 threaded thereonand suitably pinned thereto. The head 158 is provided with an inneralignment sleeve like bearing portion 160 which is used for aligning andcentering the refractory sleeve portion 162 of the piston assembly 150at its lower end thereof. Another similar sleeve portion 164 is likewiseprovided at the top of the refractory sleeve 162. A tubular member 166fits about the rod 156 and bears against the top surface of the cylinder154. The top of the member 166 is suitably connected to the upper end ofthe rod 156 which is in turn attached to a holder 168 by means of thethreads 170. The holding device 172 is identical to the device shown inFIGURE 5. The holddown member 174 is also similar to the member shown inFIGURES 1 and 2. If desired, a top centering and alignment plate 176 maybe provided above the holddown member 174 and is suitably securedthereto. The bottom seal lassembly 152 consists of a pair of sealingmembers and an insert 17S. The insert 178 is mounted by means of aninterference fit in the neck portion 180 of the gooseneck 182 and sealmembers 183 and 184 are provided at the interface surfaces 186 and 188respectively. A refractory cup or sleeve 189 may be employed to protectthe head 158 against corrosion by impinging metal during the fillingcycle. The operation of this embodiment is no different from theoperation of the apparatus described with reference to FIG- URES 1 and 2and therefore no further description is required for an understanding ofit.

The following examples illustrate the successful operation of anapparatus embodying the invention and they are not intended to limit theinvention. In all of the ex- -amples the refractory c-omponents were oftitanium diboride.

Example I A half pound casting w-as cast in the apparatus shown inFIGURE l at a rate of 240 castings per hour. The die casting -alloywhich was cast at 1225 F. was a 380 aluminum alloy and the castingpressure was 1400 p.s.i. All castings exhibited good surface finish, andwere of excellent density, exhibiting low porosity. Three thousandcastings were manufactured in this run. Subsequent inspection of theshot cylinder and the piston indicated no measurable wear.

Example II A h-alf pound casting was cast in the apparatus shown inFIGURE 1 using t-he same material as noted in Example I except that thepiston arrangement used was that as shown in FIGURE 5. Castingtemperature of the aluminum was 1250 F. and an injection pressure of1200 p.s.i. was used. A total of 1000 castings were made in this run andIall castings exhibited excellent surface finish and were of extremelyhigh density. Castings were made at a rate of 240 per hour andsubsequent inspection of the refractory components showed no measurablewear.

Example III A half pound casting composed of grade 380 aluminum alloywas cast using the type of apparatus shownrin FIG- URE 1, and the-refractory piston of the type shown in FIGURE 5, except that a slotplaced on the O.D. of the bottom section of the piston was used as thefilling port for the molten aluminum; the cylinder in this case had noapertures for filling with molten aluminum. The casting temperature ofthe aluminum was 1270 F. and the injection pressure was 1200 p.s.i. Acasting rate of 240 castings per hour was maintained. Subsequentinspection of the refractory parts showed no measurable wear.

Example 1V A half pound casting composed of grade 380 aluminum alloy wascast using t-he type of apparatus shown in FIG- URE 1 except that therefractory piston was of the configuration shown in FIGURE 7. Thecasting temperature of the aluminum was 1250 F. and the injectionpressure was 1000 p.s.i. Castings were made at a rate of 240 per hour.Su-bsequent inspection of the refractory components showed no measurablewear.

Example V A pump or refractory cylinder, used in the apparatus shown inFIGURE 1 with piston type shown in FIGURE 5, was used to cast severalhundred half pound castings with grade 380 aluminum. The castingtemperature of the aluminum was 1250" F. and an injection pressure of1200 p.s.i. per square inch was maintained. After several hundredcastings were made, the refractory parts were removed. The samerefractory cylinder and piston were used a second time in the same typeof apparatus as shown in FIGURE 1. A total of 1000 castings were made inthis run at a casting rate of 240 castings per hour. rI'he temperatureat which the aluminum was cast was 1250 F. and the injection pressurewas 1200 p.s.i. The castings exhibited excellent surface finish and wereof high density with a porosity less than that of cold chamber castings.Subsequent to removal, the same refractory cylinder and piston was useda third time to make identical castings of the same material usedheretofore. This time the casting temperature was 1170 F. and theinjection pressure was 1200 p.s.i. The castings exhibited excellentsurface finishes again. A fourth and fifth run using the same piston andcylinder were made at a casting temperature of 1170 F. `and at aninjection pressure of 1-200 p.s.i. These castings also exhibited theexcellent properties described hereinbefore. Subsequent to all fiveruns, the refractory parts were removed and upon inspection, showed nomeasurable wear.

It should be lapparent from the foregoing that many modifications andchanges in the construction and arrangement of the parts may be madewithout departing from the spirit and scope of the invention andtherefore it is intended that lall matter contained in the abovedescription or shown in the accompanying drawing shall be interpreted asillustrative and not in a limiting sense. For example, the piston andcylinder assembly may be fed from a reservoir instead of being submergedin the molten metal and the die casting apparatus may be of horizontalor inclined construction rather than the vertically described embodimentdisclosed herein.

What is claimed is:

1. The combination of a die casting machine for casting high meltingpoint die casting alloys including a holding furnace having a potcontaining molten metal to be cast and a gooseneck suspended from a yokeinto said pot and communicating with a die cavity, a shot cylinderassembly comprising a cylinder having a cavity therein and at least oneintake aperture, a piston reciprocally mounted in said cavity, means forreciprocating said piston in said cavity whereby the upward stroke ofsaid pist-on opens said intake allowing said molten metal to fill saidcavity and the downward stroke closes said intake forcing said moltenmetal from said cavity through said gooseneck and into said die, andmeans for maintaining a fluid tight seal between said cylinder and saidgooseneck comprising a resilient gasket member disposed between saidcylinder and said gooseneck, said resilient gasket comprising a spirallywound laminated ring shaped metal-ceramic composite body.

2. The combination of claim 1 wherein said piston comprises a monolithicmember having a main cylindrical portion, a reduced neck portion and anenlarged head portion for enabling said piston to be secured thereaboutby said means for reciprocating said piston.

3. The combination of claim 1 wherein said piston comprises a metal studhaving a cylindrically shaped refractory sleeve member positionedthereabout, a nut threadably secured to said stud, a split hol-dingdevice having two cavities therein, the lowermost cavity being used forholding said nut in an immovable position and the uppermost cavity beingused for clamping onto a -connecting rod communicating with said meansfor reciprocating said piston.

4. The combination of claim 1 wherein said piston comprises a metal rodhaving a head portion and a removable end por-tion, a refractory sleeveportion and a tubular member disposed about the upper portion of saidrod and above said sleeve portion for maintaining said sleeve betweensaid head portion of said rod and said removable end portion.

5. The combination of a die casting machine for casting lightweight,high melting point die casting alloys including a holding furnace havinga pot containing molten metal to be cast, and a gooseneck suspended froma yoke into said pot, said gooseneck having a cavity and a connectingpassage communicating with a die cavity, a shot cylinder assemblydisposed within said cavity of said gooseneck and comprising a cylinderhaving -a cavity therein and at least one intake aperture, a pistonassembly reciprocally mounted in said cavity of said cylinder andcomprising a stud having a cylindrically shaped sleeve member tixedlypositioned to said stud, means reciprocating said piston assembly insaid cavity whereby the upward stroke of said piston assembly opens saidintake aperture allowing said molten metal to ll said cavity of saidcylinder and the downward stroke closes said intake aperture forcingsaid molten metal from said cavity through said passage of saidgooseneck and into a die, means for maintaining said cylinder and saidgooseneck in alignment and means for maintaining a fluid tig-ht sealbetween said cylinder and said gooseneck comprising disposing a sealring between said gooseneck and said cylinder, said seal ring beingprovided wit-h an annular groove containing a seal member.

6. The combination of claim 5 wherein said seal member is a corrosionresistant, resilient metal-ceramic composite body.

CTI

7. The combination `as defined in claim 5 wherein said seal member is aspirally wound laminated ring shaped metal-ceramic composite body.

8. rIhe combination as defined in claim 5 wherein said seal ring isprovided with an annular groove containing a seal member.

9. The combination as defined in claim S wherein said seal member is aresilient, corrosion resistant, spirally Wound laminated ring shapedmetal-,ceramic composite body.

10. The combination of claim 5 wherein said means for maintaining aiiuid tight seal between said cylinder and said gooseneck and formaintaining said cylinder and said gooseneck in alignment comprises acylinder head and a holddown clamping member, said cylinder head beingprovided with a set of conical surfaces which respectively mate withcorresponding conical `surfaces on the inner diameter of said cylinderwhile said die casting machine is at high temperatures and on the outerdiameter while at lower temperatures.

11. The combination of claim 10 wherein said cylinder is provided with aprotective sleeve -secured to said holddown clamping member.

l2. The combination of claim 5 wherein said piston assembly comprises astud having a cylindrically shaped refractory sleeve member positionedthereabout, a nut threa-dably secured to said stud, a split holding`device having two cavities therein, the lower-most cavity being usedfor holding said nut in an immovable position and the uppermost cavitybeing used for clamping onto a connecting rod communicating with s-aidmeans for -reciprocating said piston.

References Cited by the Examiner UNITED STATES PATENTS 2,145,448 l/1939ILester 22--70 2,145,553 l/1939 Morin 22-70 2,295,521 9/'1942 Payne etal. 92-248 2,660,769 12/1953 Bennett 22-70 2,835,005 5/1958 Green 22-703,179,295 4/1965 yMorin 22-70 XR I3,203,056 8/ 1965 Thompson et al.22-68 3,234,605 2/ 1966 Thompson 22-70 I. SPENCER OVER'HOLSER, PrimaryExaminer.

R. S. ANNEAR, Assistant Examiner.

5. THE COMBINATION OF A DIE CASTING MACHINE FOR CASTING LIGHTWEIGHT,HIGH MELTING POINT DIE CASTING ALLOYS INCLUDING A HOLDING FURNACE HAVINGA POT CONTAINING MOLTEN METAL TO BE CAST, AND A GOOSENECK SUSPENDED FROMA YOKE INTO SAID POT, SAID GOOSENECK HAVING A CAVITY AND A CONNECTINGPASSAGE COMMUNICATING WITH A DIE CAVITY, A SHOT CYLINDER ASSEMBLYDISPOSED WITHIN SAID CAVITY OF SAID GOOSENECK AND COMPRISING A CYLINDERHAVING A CAVITY THEREIN AND AT LEAST ONE INTAKE APERTURE, A PISTONASSEMBLY RECIPROCALLY MOUNTED IN SAID CAVITY OF SAID CYLINDER ANDCOMPRISING A STUD HAVING A CYLINDRICALLY SHAPED SLEEVE MEMBER FIXEDLYPOSITIONED TO SAID STUD, MEANS RECIPROCATING SAID PISTON ASSEMBLY INSAID CAVITY WHEREBY THE UPWARD STROKE OF SAID PISTON ASSEMBLY OPENS SAIDINTAKE APERTURE ALLOWING SAID MOLTEN METAL TO FILL SAID CAVITY OF SAIDCYLINDER AND THE DOWNWARD STROKE CLOSES SAID INTAKE APERTURE FORCINGSAID MOLTEN METAL FROM SAID CAVITY THROUGH SAID PASSAGE OF SAIDGOOSENECK AND INTO A